The Pediatric Emergency Medicine Research Training Program (PEMRTP), established in 2001, offers unique multi-disciplinary training for MD and PhD biomedical researchers to acquire the skills necessary to conduct investigations of the acute illnesses and injuries that form the clinical basis for the subspecialty of pediatric emergency medicine. Twenty-eight percent of acute care in the US begins in the emergency department. Nineteen million children make more than 29 million visits to emergency departments in the United States each year. A parent can think of no more important research agenda than that their acutely ill and injured child receive the best, evidence-based care with the most effective diagnostics and treatments possible. The NIH recognizes the importance of emergency medicine research and has recently designated a trans-NIH Office of Emergency Care Research (OECR) within the National Institute of General Medical Sciences (NIGMS) to foster basic, translational, and clinical research and training for the emergency setting. The National Institute of Child Health and Human Development (NICHD) Director is one of four members of the OECR Steering Committee. This T32 competing renewal leverages the assets of Boston Children's Hospital, which includes the largest pediatric emergency medicine faculty in the world, and draws on core strengths to create a culture of rigorous research and research training to: (1) prepare individual trainees as independent researchers; and (2) fill the critical need for early and mid-career research mentors for the next generation of pediatric emergency medicine trainees here and elsewhere. Trainees develop toward independence in three interrelated phases: (1) a mentored research project; (2) formal course work; and (3) preparation of a research grant. Trainees complete either an MMSc or MPH degree. They are mentored in their laboratory of choice. And finally, with guidance from a faculty mentor, they prepare a K-99/R00 or similar mentored research grant application to facilitate their transition to independent faculty. Boston Children's Hospital and Harvard Medical School, by the breadth and depth of their research laboratories, operational, real-world clinical systems, formal academic programs, experienced faculty, and linkages to multisite research networks, provide an unparalleled environment for mentoring trainees to become future leaders. PEMRTP specifically builds on the international reputation of Boston Children's Hospital in biomedical informatics and genomics, and seeks to train our fellows to use the tools from these fields to exploit the pediatric emergency department as a laboratory for clinical and population research.